00:01
So in this example, we are given a proton moving in a magnetic field, and we are asked to find the magnetic force with three different angles that it's approaching the magnetic field.
00:12
So in part a, we are told it's perpendicular, so theta is equal to 90 degrees.
00:23
So we can write our equation for the magnetic force equal to qbb, b, b, sine, theta.
00:37
And in this case, since theta is 90 degrees, sign of 90 degrees is just equal to 1.
00:42
So the force then just becomes q, b, b.
00:48
So we know the charge of a proton is 1 .6 times 10 to the minus 19 couloms.
00:57
And then we know, well, we're given the velocity is 2 .5 times 10 to the 5 meters per second.
01:05
And we are given a magnetic field of 0 .5 tesla.
01:13
And if you multiply this out, we get a force equal to 2 times 10 to the minus 14 newtons.
01:29
So this is our answer for part a.
01:34
And then for part b, we are told when it's moving in at 30 degrees...